Whatever the structure of a cable, there must be provisions for splicing transmission media at an end of a given length of cable to corresponding transmission media at an adjacent end of another length of cable. Closures are used in the splicing of metallic conductor and of optical fiber cables.
For example, an optical fiber splice closure with a central transverse bulkhead has been used. Individual optical fibers are spliced and are attached to the bulkhead for support. A disadvantage of this approach is the lack of facilities for the storage of slack in the fibers. In other splicing arrangements, all the optical fibers in a cable are looped within the same retainer or fiber slack is stored on spools. In either case, identification, repair or splice work of individual fibers is extremely difficult without a major rearrangement within the splice closure. This is undesirable because the transmission capability in active fibers can be affected as they are moved.
In another closure of the prior art, there is provided a device for organizing a plurality of individual optical fibers or other similar type conductors or fibers at a slack or splice point. A device having modular construction is provided which is suitable for installation in standard splice closures. The device comprises a plurality of tray-like members each adapted to retain and store at least one fiber. The device provides access to the individual fibers contained in the trays.
It is important that the cables extending into or out of the closure be held tightly to prevent undesired movement of portions of the cable inside the closure. Should the cable move, movement of conductors will be experienced. Such movement of conductors may have an adverse effect on communications signals passing through the conductors within the closure and break the seal between the grommet and the cable passing therethrough.
In the past, a metal member extended from an inner end plate toward an outer end plate. Annular worm-gear clamps were disposed about each cable to hold the cable to the metal member in a secured position. This arrangement prevents each cable from being pulled out, but it does not prevent cable sealing members which are referred to herein as grommets from being displaced. The inner cable grommet may be displaced because of air pressure within the closure which is used to check the integrity of the seals.
Also needed is support for the outer cable grommets located in the outer end plate. External forces such as water pressure or ice formation may cause the outer grommets to be pushed inwardly.
Further, each closure should be capable of being used with a range of cable sizes. In the past, metal hardware had to be bent by a user to conform to different size cables. What is sought after is a sheath gripping device which can accommodate a range of cable sizes.
Another disadvantage of prior art sheath grips resides in electrical shorting. A metal bracket is commonly attached to cables entering the closure through the outside end plate. In the past, the metal sheath grip bracket sometimes contacted bonding and grounding devices attached to the metallic elements of the cable thereby causing a short out. It is desired to overcome this failing of prior art sheath grips because it sometimes is desirable to isolate electrically one cable from another.
What is needed and what is not provided in the prior art is a cable closure which includes a cable sheath grip which avoids short outs with neighboring metallic elements and which can accommodate a range of cable sizes. The sought after cable sheath grip also should provide support for grommets in end plates of a cable closure and should be easy and quick to install.